44 



THE EMBRYOLOGY OF THE HONEY BEE 



The blastoderm covering the ventral and lateral faces of the 

 egg, as already described (p. 40), is a thick single layered epi- 

 thelium composed of slender prismatic cells. Its average thick- 

 ness is greatest in the anterior region of the egg and decreases 

 slightly and gradually toward the caudal pole. This division, 

 composing the major portion of the blastoderm, is the distinctly 

 embryonic portion, since it alone contributes directly to the for- 

 mation of the embryo. 



On each side of the dorsal strip is a band comprising some 

 four to six longitudinal rows of cells whose central ends are very 

 clear and transparent (Fig. 19, Am). Those cells next to the 



Am 



FIG. 19. Transverse section through the anterior region of an egg, 

 Stage IV, showing dorsal strip of blastoderm (DS), amnion forming cells 

 (Am), middle plate (MP) and lateral plates (LP}, x 243. 



dorsal strip are triangular in outline when seen in transverse sec- 

 tion, and in contact with the dorsal strip at one corner ; all the 

 cells of this strip are less slender than the cells of the embryonic 

 blastoderm (2), many of them approaching the cubical form. 

 Those lying nearest the embryonic blastoderm intergrade with 

 the cells of the latter, so that the lateral limits of this division of 

 the blastoderm cannot be determined with precision until the 

 formation of the germ layers is well under way. These two 



